A method for sealing a flexible liner that has been emplaced in a borehole manifesting artesian water flow. The upper end of the liner is closed with a plug, and a mud tube is extended from the plug down to a small volume of mud at the bottom end of the liner. The pressure in the liner interior is increased according to the weight of the mud column in the mud tube. pressure in the liner interior can be regulated by allowing mud to move up and down in the mud tube, and by adding or withdrawing water from the closed liner interior.
|
1. A method for sealing a flexible liner disposed in a borehole having a wall, comprising:
placing a volume of weighted mud in a liner interior;
at least partially filling the liner interior, above the volume of weighted mud, with water;
sealing with a plug an upper end of the liner;
installing a mud tube through the plug and extending the mud tube in the liner interior between the plug and the volume of weighted mud;
adding water into the liner interior, between the plug and the volume of weighted mud, to dilate the liner toward the borehole wall;
at least partially filling the mud tube with a flowable mud; and
moderating a pressure in the liner interior by:
sealing a top of the mud tube;
filling the mud tube partially with water;
trapping a volume of air in an upper portion of the sealed mud tube; and
allowing changes in the pressure in the liner interior to be offset by an expansion or a contraction of the volume of the air trapped in the upper portion of the sealed mud tube.
12. A method for sealing a flexible liner disposed in a borehole having a wall, comprising:
placing a volume of weighted mud at a lower portion of a liner interior;
at least partially filling the liner interior, above the volume of weighted mud, with water;
sealing with a plug an upper end of the liner;
installing a mud tube through the plug and extending the mud tube in the liner interior between the plug and the volume of weighted mud; and
at least partially filling, to a first level, the mud tube with a heavy flowable mud to increase a pressure in the liner interior;
adding water into the liner interior to increase further the pressure in the liner interior;
displacing upward, with the increased pressure, the flowable mud to a second level in the mud tube, thereby maintaining the increased pressure in the liner interior;
wherein adding water into the liner interior further comprises providing tube or hose means for withdrawing water through the plug, and further comprising regulating the pressure in the liner interior by controlling with a valve a flow of water from the liner interior.
2. The method of
3. The method of
4. The method of
5. The method of
6. The method of
withdrawing water from the liner interior; and
permitting flowable mud to descend in the mud tube.
7. The method of
8. The method of
9. The method of
10. The method of
11. The method of
13. The method of
14. The method of
15. The method of
16. The method of
filling the mud tube, above the flowable mud and to a top of the mud tube, with water; and
sealing a top of the mud tube, thereby limiting displacement of the mud within the mud tube.
17. The method of
|
This application claims the benefit of the filing of U.S. Provisional Patent App. Ser. No. 61/793,548 entitled “Method for Sealing of a Borehole Liner in an Artesian Well” filed on 15 Mar. 2013, and the specification thereof is incorporated herein by reference. This application is related to U.S. Utility patent application Ser. No. 14/205,480 entitled “Method of Installation of Flexible Borehole Liner Under Artesian Conditions” filed on 12 Mar. 2014, the specification of which is incorporated herein by reference.
Field of the Invention
This invention relates to the development of a safe interior pressure in order to affect the seal of flexible borehole liners in boreholes in geologic formations with shallow water tables or formations exhibiting artesian hydraulic head conditions. The liner may or may not be installed in the borehole by pressurized eversion.
Background Art
A “borehole” is a hole, e.g., a drilled shaft, into the Earth's subsurface. The hydraulic conductivity profiling techniques described in my U.S. Pat. Nos. 6,910,374 and 7,281,422, whose teachings are incorporated herein by reference, have been used in over 300 boreholes since 2007. These patents describe a hydraulic transmissivity profiling technique which carefully measures the eversion of a flexible borehole liner into an open, stable, borehole.
Liners are usually installed into the open boreholes using a water level inside the liner which is significantly higher than the water table in the formation penetrated by the borehole. However, when such a desirable excess head is not available within the borehole, a scaffold and an extension of the surface casing, above the ground's surface, are often used to obtain the higher water level within the liner to achieve the pressure head needed during the installation of the liner. The continued presence of a scaffold and/or casing extension is usually an objectionable means for providing long-term pressurization of the flexible liner adequately to seal the borehole. In other situations, the inventor of the invention hereinafter disclosed has filled the liner with a weighted mud to achieve an interior pressure sufficient to seal the liner against the artesian head in the formation. In a deep borehole, however, the mud density required to seal the borehole throughout an upper portion of the hole produces such a high pressure at the bottom of the borehole as to risk bursting of the borehole liner. The present invention ameliorates or eliminates the risk of busting the liner, while yet promoting a reliable sealing of the borehole by the liner.
With the foregoing background, the presently disclosed invention was developed.
The invention described hereafter allows an installed liner (installed by eversion or otherwise) to be pressurized in a manner similar to the use of a tall casing extension above the ground surface. However, the “virtual” casing extension of the present invention is located interior to the borehole, and does not interfere with the ground surface appearance, or with the use of above-ground equipment, after the liner is installed. Furthermore, the following method and apparatus does not require the filling of the entire length/depth of liner with a weighted mud, and thus avoids the development of excessive pressures at the bottom of the liner which otherwise undesirably occurs.
There is disclosed herein a method and apparatus to maintain an elevated pressure inside a flexible liner located in a borehole, such that the liner provides a competent seal of the borehole. This method and apparatus allow the convenient pressurization of a liner in circumstances of artesian conditions or shallow water tables, where a known method, using an elevated water level inside the liner (e.g. well casing extension high above ground surface), is not possible with a particular borehole. The present method uses the gravitational force upon a heavy mud column to obtain a sufficient increase of the pressure inside the liner. The desired elevated pressure inside the liner is achieved by adding a weighted mud to an interior mud tube and sealing the top end of the liner. The heavy mud column descends under the force of gravity so as to partially fill the bottom end of the liner, and thus causes an increase in the interior pressure of the water trapped inside the liner. Only a small amount of mud fill in the bottom of the liner is needed to increase the water pressure inside the liner. Accordingly, unlike previous methods of installation of a heavy mud fill of the liner, this presently disclosed method uses primarily an ordinary water fill in a major portion of the liner's interior volume. With a water fill of the liner, excessive pressures do not develop at the bottom of the liner, which otherwise are possible with a complete mud fill of the liner. A central aspect of the invention is to seal a liner in a shallow to artesian water table situation, with the advantage of using only a small quantity of mud (a good savings) or grout (a great savings). The advantage of not having an increasing pressure, as in a tall mud column standing in the liner interior nearly to the ground surface, is a great reduction of risk of liner blow-out. Rather, a flowable mud instead sands in the narrow-diameter mud tube extending to the bottom of the installed liner. Also, the ability to adjust the liner pressure to a wide range of pressures is a great advantage.
Other advantages and devices associated with this method will be described.
The attached drawings, which form part of this disclosure, are as follows:
If the water table depth in the formation 17 is less than the necessary distance below the top of the casing 13, one can extend the surface casing upward (above the surface of the ground) to obtain a higher driving pressure inside the liner. There are, however, practical safety limits as to how high the casing can be so extended, with the associated surrounding scaffolding for work space for the installation personnel. Casing extensions for this purpose are cumbersome and to be avoided when possible.
In the borehole 27 seen on the left side of
The invention described in my co-pending Utility Patent Application Ser. No. 14/205,480, filed on 12 Mar. 2014, and entitled “Method of Installation of Flexible Borehole Liner Under Artesian Conditions,”allows a liner to be everted into a borehole with a very high artesian water table. Whereas that apparatus and method is most useful in allowing a liner to be installed with a very elevated water level 23 (right side of
The present disclosure does not assert that the use of a heavy mud for installing liners is an innovation in itself worthy of patent protection. Such practice has been in use for many years in order to obtain a sufficient excess head in the liner to seal the borehole with the liner water level such as level 22 seen in
Reference is invited to
There now is provided disclosure of process and procedure for installing and sealing an everting liner to obtain the configuration depicted in
There next follows a step of partially filling the liner interior, above the volume of weighted mud, with water; the upper portion of the liner, above the small volume of mud 32, is filled with water (e.g., to the level 313). In
Attention is invited to
Water is added into the liner interior 511 between the plug and the volume of weighted mud. A hose 59 connection into the sealing plug 54 allows water to be added to the interior 511 of the liner 51, and the interior of the liner (above the small volume of mud 32 placed at the liner bottom 315 earlier in the process (
The steps of the method of the invention include at least partially filling the mud tube with a flowable mud. The mud tube 52, which penetrates the plug 54 and extends into the liner interior 511, is then filled partially or entirely with a heavy mud 53 delivered from any suitable container at the top end of the tube 52 (i.e., at the ground's surface). As depicted in
The mud tube 52 is at least partially filled with a flowable mud; any mud added into the mud tube increases the pressure inside the liner, as a result of the liner interior 511 being plugged closed (unless deliberately opened at the plug 54 to permit venting of the interior). Because the liner 51 is sealed, the addition of mud 53 via mud tube 52 increases the pressure of the water fill in the liner interior 511, until the water pressure is sufficiently high to prevent any further descent of the heavy mud 53 in the tube 52.
The pressure in the liner interior 511 can be regulated and adjusted by adding or removing water to or from the closed liner interior, by means of the valve 57 and hose 59. If the pressure within the liner interior 511 exceeds a desired value, water can be removed; the valve 57 is opened to permit some water to flow from the liner interior (via a passage through the plug 54) until the mud column 53 descends in the tube 52 to provide the desired pressure within the liner. At that time, the valve 57 is closed, and the water pressure within the liner is higher than the pressure head in the formation 55, causing the liner 51 to press sufficiently against the borehole wall to seal reliably the borehole. Due to the gravitational force on the mud 53 in the mud column, which is of significantly higher density than the water inside liner, the desired pressure is maintained in the interior 511 of the impermeable liner interior 51.
If there is any subsequent small amount of water leakage from within the liner, the mud column 53 in tube 52 descends to maintain a slightly lower pressure in the liner. This is a significant advantage of the mud 53 column standing in the tube 52. In previous attempts to maintain a constant pressure in liner interior 511 with the addition of air through a sealing plug, the air diffused through the liner 51, or dissolved in the water within the liner, and the liner pressure dropped below the minimum level needed to provide a reliable seal of the borehole by the liner.
The mud-filled tube 52 maintains the pressure within the liner needed to dilate the liner against the borehole wall. Accordingly, there is no need for a tall stand pipe or casing extension above the ground's surface to provide the necessary long term pressurization of the liner under circumstances of artesian pressure in the formation 55. It is much easier to seal the liner 51 against water leakage than against air leakage. The elimination of a standpipe above the surface casing of the borehole is an advantage of the present apparatus and method.
An important aspect of this system and method is that the water column throughout the length/depth of the liner interior 511 has a constant excess head over the ambient formation pressure. If the heavy mud were used to fill the entire liner, the over pressure in the liner would be a function of the depth of the mud in the liner. In that case, the overpressure in the liner would be:
ΔP=(ρ−1)D
where ρ is the density of the mud and D is the depth below the surface of the mud in the liner. For deep boreholes, the excess pressure inside the mud filled liner may exceed the burst pressure of the liner. In the current system and method, the only mud contacting the inside of the liner is the small amount of weighted mud 32 disposed in the bottom end 315 of the liner (
A typical mud used for this method may be a mix of a clay (such as bentonite) and a powdered, high density mineral such as barium sulfate, which has a grain density of 4.1 gm/cc. The heavy barite powder and bentonite mix remains plastic and the bentonite forms a gel which prevents the settlement of the powdered mineral. It has been observed that without the thixotropic property of the clay mineral, the heavy powder settles over a long time and forms a mass of high shear strength, which can prevent the inversion of the liner for its convenient removal from the borehole. The mud mixture must have a sufficient gel strength for support of the weighting material, but also must exhibit sufficiently low shear strength so as to allow the mud to flow in the mud tube, as needed, to maintain the pressure in the liner. While significant to the practice of the present invention, these mud properties are of common determination, selection and use in the drilling industry. Tests of mud mixtures provided data on the mud properties meeting the needs of the present system and method. It is possible to support the weighting material, and still allow the mud to move in the mud tube, with approximately 1.0 psi change in the liner pressure. The diameter of the mud tube 52 can also be adjusted to allow favorable mud behavior. The larger the mud tube diameter, the more easily the mud 53 can flowably move up/down in the tube to accommodate pressure changes in the liner.
Although the weighted mud 53 described is a common suitably heavy liquid, any suitable heavy liquid can be used in the practice of this invention instead of the mud. Thus in this disclosure and the claims, “mud” refers to any suitable heavy liquid. Common muds are somewhat erratic in their properties of the mixture due to pH and water quality effects. Attractive alternative options for a heavy liquid in lieu of heavy mud are polymer mixtures such as are used in drilling oil wells.
Another attractive feature of the present invention is that the pressure in the mud tube 52 can be increased by application of air pressure at the top of the mud tube (
The filling of the mud 53 in the tube 52 can be effectuated by pressurizing the liner interior with water by means of the water addition hose 59 and valve 57. The increased liner interior pressure will force mud upward in the tube until it reaches a level whereby the mud column pressure (of the tube 52) equals the pressure in the liner interior 511. In a like manner, if the tube 52 is sealed at the top and filled partially with air and/or partially with water, an increase of the liner pressure will raise the mud or water level in the tube until it compresses the air to achieve a water pressure in the tube in equilibrium with the pressure of the liner interior. Any subsequent change in the liner pressure will be offset by an expansion or contraction of the volume of air trapped in the upper portion of the sealed tube 52. With these several mechanisms, a liner interior pressure change is moderated in the event of any liner leakage, or other cause for a pressure change in the liner interior.
It is common for the artesian pressure in the formation 55 to increase after a rain storm. Such an increase could collapse an ordinary liner filled with mud or water when the top of the liner is not sealed. The liner collapse can lead to loss of the liner seal of the borehole. However, with the sealed liner of this design, an increase in the artesian pressure also causes an increase in the liner interior pressure. This is because the liner 51 is elastic, such that an increase in the formation's artesian pressure decreases the differential pressure across the liner. That decrease causes the liner to contract, and thereby increases correspondingly the internal pressure of the liner. The space for accommodating the liner volume change is the usual breakouts and other voids in the wall of the borehole adjacent the liner. The elasticity of the normal liner made of a nylon fabric is very useful for this beneficial behavior. This compensating effect is best if the tube 52 is filled to its top with water or mud, and sealed. However, in order to allow the fill of the mud tube to descend in the event of a decrease of the liner pressure, a one-way check valve should be located in the sealed end to allow air to enter but prevent fluid flow out of the top of the mud tube.
Where the present disclosure shows a means and method of maintaining a constant over-pressure inside a blank liner, the same method can maintain the pressure desired inside of other types of flexible borehole liners.
Accordingly, there is disclosed a method for sealing a flexible liner 51 disposed in a borehole 56 having a wall, comprising the basic steps of: placing a volume of weighted mud 32 at a lower portion 315 of the liner interior 511; at least partially filling the liner interior, above the volume of weighted mud, with water; sealing with a plug 54 an upper end of the liner 51;
installing a mud tube 52 through the plug 54 and extending the mud tube in the liner interior 51 between the plug 54 and the volume of weighted mud 32; and at least partially filling, to a first level, the mud tube 52 with a heavy flowable mud to increase a pressure in the liner interior 511. Adding water into the liner interior 511 preferably includes providing a tube or hose means for withdrawing water through the plug, and further comprising regulating the pressure in the liner interior by controlling with a valve 57 a flow of water from the liner interior. The method also includes the steps of adding water into the liner interior 511 to increase further the pressure in the liner interior, and displacing upward, with the increased pressure in the liner interior, the flowable mud 32 to a second level in the mud tube 52, thereby maintaining the increased pressure in the liner interior.
Also according to the invention, pressure in the mud tube 52 is increased by applying air pressure at the top of the mud tube. Preferably there is disposed a check valve 530 in the mud tube 52 for maintaining increased pressure in the mud tube. Adding water into the lining interior 511 may be done to replace any water loss from the liner interior, to increase to the first level a height of the mud 32 in the mud tube. The method also features (1) filling the mud tube 52, above the flowable mud in the mud tube and up to a top of the mud tube, with water, and then (2) sealing a top of the mud tube, thereby limiting displacement (especially upward) of the mud within the mud tube. The sealing of the top of the mud tube 52 may include disposing the check valve 530 in the mud tube 52 to allow air to flow into the tube but to prevent fluid flow, including mud or water, from the top of the mud tube.
Only some embodiments of the invention and but a few examples of its versatility are described in the present disclosure. It is understood that the invention is capable of use in various other combinations and is capable of changes or modifications within the scope of the inventive concept as expressed herein. Modifications of the invention will be obvious to those skilled in the art and it is intended to cover in the appended claims all such modifications and equivalents.
Patent | Priority | Assignee | Title |
10030486, | Jun 22 2015 | Method for installation or removal of flexible liners from boreholes | |
10337314, | May 28 2015 | Shallow ground water characterization system using flexible borehole liners | |
10837263, | Nov 06 2015 | TYRFING INNOVATION AS | Installation apparatus and method |
10954759, | Oct 24 2018 | Method for increasing pressure in a flexible liner with a weighted wellhead | |
11085262, | Jan 17 2019 | Method of installation of a flexible borehole liner without eversion | |
11143001, | Jun 06 2019 | Optimal screened subsurface well design | |
11319783, | Dec 05 2019 | Method for guiding the direction of eversion of a flexible liner | |
11585211, | Dec 09 2019 | Flexible liner system and method for detecting flowing fractures in media |
Patent | Priority | Assignee | Title |
1407873, | |||
2626778, | |||
4778553, | Apr 16 1986 | INSITUFORM NETHERLANDS B V | Method of lining a pipeline with a flexible tubular sleeve |
5176207, | Aug 30 1989 | EVI CHERRINGTON ENVIRONMENTAL, INC | Underground instrumentation emplacement system |
5246862, | Mar 24 1993 | The United States of America as represented by the Secretary of the Army | Method and apparatus for in-situ detection and determination of soil contaminants |
5377754, | Mar 02 1994 | Progressive fluid sampling for boreholes | |
5803666, | Dec 19 1996 | Horizontal drilling method and apparatus | |
5804743, | Aug 20 1996 | General Electric Company | Downhole passive water sampler and method of sampling |
5853049, | Feb 26 1997 | Horizontal drilling method and apparatus | |
6026900, | Jun 15 1998 | Multiple liner method for borehole access | |
6109828, | Apr 17 1997 | Horizontal drilling method | |
6244846, | Nov 17 1998 | Pressure containment device for everting a flexible liner | |
6283209, | Feb 16 1999 | Flexible liner system for borehole instrumentation and sampling | |
6601449, | May 24 2001 | Self-regulating bubble tube assembly | |
6910374, | Oct 08 2002 | Borehole conductivity profiler | |
7281422, | Sep 04 2003 | Method for borehole conductivity profiling | |
7753120, | Dec 13 2006 | Pore fluid sampling system with diffusion barrier and method of use thereof | |
7841405, | May 05 2006 | Flexible borehole liner with diffusion barrier and method of use thereof | |
7896578, | Jun 28 2007 | Mapping of contaminants in geologic formations | |
8069715, | Oct 15 2007 | Vadose zone pore liquid sampling system | |
8176977, | Feb 25 2008 | Method for rapid sealing of boreholes | |
8424377, | Jun 17 2009 | Monitoring the water tables in multi-level ground water sampling systems | |
20070113638, | |||
20120173148, | |||
CN100436341, | |||
CN101024540, |
Executed on | Assignor | Assignee | Conveyance | Frame | Reel | Doc |
Date | Maintenance Fee Events |
Mar 01 2021 | M2551: Payment of Maintenance Fee, 4th Yr, Small Entity. |
Date | Maintenance Schedule |
Oct 24 2020 | 4 years fee payment window open |
Apr 24 2021 | 6 months grace period start (w surcharge) |
Oct 24 2021 | patent expiry (for year 4) |
Oct 24 2023 | 2 years to revive unintentionally abandoned end. (for year 4) |
Oct 24 2024 | 8 years fee payment window open |
Apr 24 2025 | 6 months grace period start (w surcharge) |
Oct 24 2025 | patent expiry (for year 8) |
Oct 24 2027 | 2 years to revive unintentionally abandoned end. (for year 8) |
Oct 24 2028 | 12 years fee payment window open |
Apr 24 2029 | 6 months grace period start (w surcharge) |
Oct 24 2029 | patent expiry (for year 12) |
Oct 24 2031 | 2 years to revive unintentionally abandoned end. (for year 12) |